package utils;

import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.http.HttpRequest;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Map;


public class SimpleBeanConvertor {

    public static <T> T convert(HttpServletRequest request, Class<T> targetType) throws InstantiationException, IllegalAccessException, InvocationTargetException {
        Map<String, String[]> params = request.getParameterMap();

        if (params.size() == 0) return null;
        T target = targetType.newInstance();
        //获取JavaBean中的所有方法
        Method[] allMethods = targetType.getMethods();
        if (allMethods != null && allMethods.length > 0) {
            for (Method method : allMethods) {
                if (method.getName().startsWith("set")) {
                    Class[] args = method.getParameterTypes();
                    if (args.length == 1) {
                        String paramName = method.getName().substring(3, 4)
                                .toLowerCase() + method.getName().substring(4);
                        if (params.containsKey(paramName)) {
                            try {
                                Object value = parseValue(params.get(paramName), args[0]);
                                method.invoke(target, value);
                            } catch (InvocationTargetException e) {
                                throw new RuntimeException(e);
                            } catch (ParseException e) {
                                throw new RuntimeException(e);
                            } catch (UnsupportedTypeException e) {
                                throw new RuntimeException(e);
                            }
                        } else if (Boolean.class == args[0] || boolean.class == args[0]) {
                            method.invoke(target, false);
                        }
                    }
                }

            }
        }

        return target;
    }


    /**
     * 将HTTP请求String类型的参数值转换为相关属性的类型
     *
     * @param value
     * @param type
     * @return
     * @throws ParseException
     */
    private static Object parseValue(String[] value, Class type) throws ParseException, UnsupportedTypeException {
        if (String.class == type)
            return value[0];
        if (java.util.Date.class == type)
            return new SimpleDateFormat("yyyy-MM--dd").parse(value[0]);
        if (boolean.class == type || Boolean.class == type)
            return true;
        if (char.class == type || Character.class == type)
            return value[0].charAt(0);
        if (int.class == type || Integer.class == type)
            return Integer.valueOf(value[0]);
        if (short.class == type || byte.class == type || long.class == type
                || float.class == type || double.class == type)
            try {
                type = Class.forName("java.lang." + type.getName().substring(0, 1)
                        .toUpperCase() + type.getName().substring(1));
            } catch (ClassNotFoundException e) {
                throw new RuntimeException(e);
            }
        if (type.getName().startsWith("java.lang.") || type.getName().startsWith("java.math."))
            try {
                return type.getConstructor(String.class).newInstance(value[0]);
            } catch (Exception e) {
                throw new UnsupportedTypeException(e);
            }
        throw new UnsupportedTypeException();
    }
}
